#include<stdio.h>
int IsAllDigit(char p[]);
int main()
{	  	 	 	     	 
    char a[80];

    printf("Please input a string:");
    gets(a);

    if (IsAllDigit(a))
        printf("The string is digit string.");
    else
        printf("The string is not digit string.");

}	  	 	 	     	 
int IsAllDigit(char p[])
{	  	 	 	     	 
    int flag = 1, i;

    for (i = 0; p[i] != '\0'; i++)
    {	  	 	 	     	 
        if (p[i] < '0' || p[i] > '9')
        {	  	 	 	     	 
            flag = 0;
            break;
        }
    }
    return flag;
}